16 
Planicart, Planitop), a DZ-5 control unit and a semi-automatic drafting | 
machine. The control circuits are partly hardwired (ROM’s) and partly pro- | 
grammable (PROM ’s) microprocessors. The basic functions are similar to those | 
of the PG-2-AT system. The Zeiss system has also been programmed for ) 
plotting closed polygons (e.g. buildings, parcels) and parallelograms. 
Serial systems with on-line computers (figure 5b) have recently gained 
increasing attention. Such systems have been developed by Wild (where EK -22 
is interfaced with a computer), Zeiss Oberkochen (where DIREC 1 is linked to 
a computer), Matra/SFOM (Long System), and Kern (with DC-2 and computer). | 
The computer is either a table-top calculator or a minicomputer, equipped € e 
with some I/O devices. 
The main advantages of such systems are considerable flexibility and 
versatility. Moreover, speed and convenience of certain operations can be 
increased. Computer's storage capacity is expandable and more peripheral 
units can be operated than in systems without a computer. Users have the 
possiblity to change and/or extend the application software. In the following 
some recently developed systems will be reviewed and their main properties 
outlined. 
Wild EK-22 (18) may also act as an interface unit between a photo- 
grammetric instrument and a table-top calculator (e.g. Hewlett Packard, 
Wang, Olivetti) or a minicomputer (e.g. Nova 2). The basic- and some appli- 
cation programmes are available. 
Zeiss Oberkochen DIREC 1 (19) is an interface unit linking analogue 
components with a table-top calculator (Hewlett Packard series) or with a 
minicomputer (DEC). The computer monitors a digital recording device or 
the DZ-5 unit for automatic drafting. A graphic CRT display terminal can be 
connected (for cartographic editing). The system provides for considerable © e 
interactivity with operator. 
Similar development has taken place also in the USA where digital ] 
drafting machines were linked, e.g. with the Zeiss Oberkochen Planimat and 
the Wild B8S Super-Aviograph. | 
Matra/SFOM Long System (20) (21) has been configured similarly to : 
the above two systems. The 950 Interface is compatible with the PDP 8 mini- 
computer, 920 Stereoplotter, 9400 Profile Digitiser, 910 Third Camera (i.e. 
orthophoto printer), 960 X-Y Table (i.e. drafting machine), and various